It may be conceivable that various services are provided for a vehicle occupant if a location of the occupant in the cabin or in the vicinity of the vehicle is detected. Vehicle occupants may carry a mobile terminal capable of wireless communication. Based on this situation, a technique has been proposed where radio waves from a mobile terminal are received using antennas installed on a vehicle or inside the vehicle cabin and thereby the location of the mobile terminal (and thus the location of the occupant) is detected.